In previous studies (J. Clin. Invest. 54-529-535, 1974) we showed that electrical feel stimulation of muscle strips 2 mm wide from the gastro-duodenal junction induced relaxation in 1 to 2 strips from all cats, opossum and the one human studied. Muscle strips from 6-8 dogs failed to relax, suggesting that this pyloric function differs in the dog. The aim of the present study is to resolve the question of species differences in pyloric function and furthermore to elucidate the role of the pylorus in controlling gastric emptying. Six dogs and four cats with simple gastric fistulas will be studied. Pyloric closure will be prevented by placing in the pylorus a teflon cannula with an internal diameter of 1-1.25 cm in dogs and about 0.6 cm in cats. This pyloric cannula will be sewn into the pyloric channel. At the completion of the initial series of tests the cannulas will be removed and the studies repeated. Thus, each animal will act as its own control. Test meals will be 240 ml and 480 ml of water, acid (120 mM HCl) and hyperosmotic glucose (555 mM) in the dogs and 50 ml of water, acid (100 mM HCl) and fat (20 mM sodium oleate) in the cats. Phenol red will be used as a non-absorbable marker. The position of the pyloric cannula will be verified in all animals either at operation or autopsy. Furthermore, Barium studies will be done soon after cannulas are placed to check that they remain in situ. Each test meal will be warmed to 37 degrees C and instilled into the stomach by the gastric fistula. Gastric contents will be drained at 15-25 minutes with the 240 ml meal, 30-40 munutes with 480 ml meal in the dogs and at 15-20 minutes in the cats. Volume of the original meal left in the stomach will be used as an index of gastic emptying. This volume represents the phenol red mass. It is predicted from these studies that the role of the pylorus in gastic emptying will be assessed in two species. Furthermore, by the amount of added gastric secretions we will be able to determine what the amount of reflux will be. BIBLIOGRAPHIC REFERENCES: Cooke, A.R.: Control of gastric emptying and motility. Gastroenterology (Part 1) 68:804-816, 1975. Stemper, T.J. and Cooke, A.R.: Gastric emptying and its relationship to antral contractile activity. Gastorenterology 69:649-653, 1975.